Coating paper



May 14, 1935; J. H. wooo COATING PAPER FiledFeb; 9, 1931 4 Sheets-Sheet 1 May 14, 1935. J. H. wooD 2,001,339

' COATING PAPER Filed Feb. 9, 1931 4 sh t s t 2 May 14, 1935. J. H. WOOD 2,001,339

- COATING PAPER Filed Feb. 9, 1931 4 s ts s et 5 122 gjafiqpk H d,

Patented May l4, 1935 UNITED STATES PATENT FFICE 2 Claims.

My invention relates to the production of enameled paper, and includes among its objects and advantages an improvement in quality and a reduction in the cost of that portion of the process involving the application of the enamel to the paper.

In the accompanying drawings:

Figure 1 is a diagrammatic view of a system employed for applying enamel coating to paper;

Figure 2 is a sectional view taken along the line 2-2 of Fig. 1;

Figure 3 is a fragmentary detail view of an equalizer roll;

Figure 4 is an enlarged sectional detailed view taken along the line 44 of Fig. 3;

Figure 5 is an enlarged sectional view of a piece of paper immediately after the enameled coating has been processed by one of the equalizer rolls;

Figure 6 is a sectional view similar to Fig. 4 showing a modified form of equalizer roll;

Figure 7 is an enlarged sectional view of a piece of paper showing the appearance of the enamel coating immediately after it has been processed by the equalizer roll shown in- Fig. 6;

Figure 8 is a fragmentary detail view of my system showing a brush associated with an equalizer roll;

Figure 9 is a sectional view indicating a stiffening support for an equalizer;

Figure 10 is a detail view showing means for separating two webs of paper as they are processed separately;

Figure 11 is a sectional view of an alternative way of using an equalizer roll;

Figure 12 is a sectional view along the line |2l2 of Fig. 11;

Figure 13 is a sectional view taken along the line I3l3 of Fig. 11;

Figure 14 is a fragmentary side elevation of the roll shown in Figs. 11, 12, and 13, illustrating the spiral winding upon the roll;

Figure 15 is a diagram indicating a manner of holding paper positively in place with respect to an equalizer;

Figure 16 illustrates a drying means;

Figure 17 is a diagrammatic view indicating a pair of equalizers arranged in series; and

Figure 18 is a diagram indicating a manner of controlling margins.

The previously universal process for applying an enamel coating to a sheet of paper, so far as I am aware, has been to get the requisite amount of the enamel onto the paper with approximate uniformity from side to side of the paper as by drawing the paper through a bath, or between a pair of wetted pinch rolls, or over the face of a rotating brush dipping into a bath of enamel. The moving web, carrying its charge, then passes under a series of fine camel hair brushes which 5 reciprocate rapidly with a relatively short stroke in a direction perpendicular to the travel of the paper and thus smooth or iron out any striations left by the applying machines.

Such brushes obviously can perform no calil0 brating or gauging function, so that reliance must be placed entirely on the original application so far as having the finished paper of the same'thickness in the middle and at the edges is concerned. The longitudinal speed of the paper 15 cannot be very many times greater than the transverse speed of the brushes, because the motion of the individual hairs in the brushes must be at a reasonable angle, and the transverse speed of the brushes is seriously limited by their tendency to pick up the enamel and throw it around in a fine atomized spray when a predetermined speed is exceeded. This limits the speed of operation of the entire machine.

I have discovered that the physical properties of the material customarily employed in applying enamel to paper are such that striations less than a predetermined size will, under favorable circumstances, equalize themselves by the flow of the material under the combined forces of gravity and surface tension or capillary-action.

Without attempting to state any theoretical explanation of how this occurs, it is a fact that I have obtained the results indicated.

According to the invention, I apply to the mov- 35 ing surface of the paper charged with enamel a rigid instrumentality operating by partial contact with the paper to positively remove from the paper enamel in excess of that permitted to pass between it and the paper through regularly spaced irregularities of contour in the portion of the element engaging the paper. One successful form of such an element is a rigid body defined by a surface of revolution upon which is superposed a fine spiral winding producing uniform serrations.

In the embodiment selected to illustrate apparatus according to the invention I make use of a pair of pedestals l0 and I2 which carry cylindrical members I4' and I6 respectively, upon which two webs of paper IB and 20 are wound. The webs l8 and 20 pass together and in contact around rolls 22 and 24. The web l8 passes under a roll 26 while the web 20 passes over a roll 28. These two rolls separate the webs l8 and 20 immediately after they have passed over the roll 24. The web I8 after passing under the roll 26 passes over an idle roll 38, over a coating roll 32, and an equalizer roll 34. The web 28, after passing over the roll 28, runs around an idle roll 36 and in contact with the web I8 around an idle roll 38. The coating roll 32 has a portion of its peripheral surface disposed within a pan 48 containing enamel coating material. The enamel coating adhering to the surface of the coating rollwill be deposited upon one side of the web I8 as the latter passes over the roll 32. In reaching the roll 38 the web I8 has received a charge of enamel and that charge has been equalized by the equalizer roll 34, while the web 28 has merely been carried along without being processed in any way.

The webs I8 and 28 after passing over the idle roll 38 pass over an idle roll 42. From this point the web I8 passes directly to a drying device. The web 28, however, passes underneath an idle roll 44, over a coating roll 46, over an idle roll 48, under a roll 52 and over an equalizer roll 58. The web 28 from this point passes to the drying device above referred to. The coating roll 46 also has a portion of its peripheral surface positioned within a pan 54 provided with a supply of the enamel coating material.

The coating rolls 32 and 46 are rotatably mounted but have no other movement with respect to the pans 48 and 54 respectively. The pans are provided with lugs 56, see Figs. 1 and 2, which have threaded openings 58 for receiving screws 68. A crank 62 is suitably mounted upon each of the lugs and is provided with a bevel gear 64 arranged in mesh with a companion bevel gear 66 threaded upon the screw 68. By turning the cranks 62 the pans 48 and 54 may be moved vertically toward or away from their respective coating rolls.

The equalizer roll illustrated in Figs. 3 and 4 comprises a cylindrical member 62 upon which is helically wound a wire 64. The convolutions of the wire are arranged in contiguous relation as will be seen in referring to Fig. 4. The convoluted surface of such an equalizer roll may be made to engage the moving surface of a web charged with enamel to positively remove the enamel in excess of a predetermined amount.

This makes the coating uniform. The convoluted surface of the equalizer roll produces a series of uniform striations 88 in the coating of enamel. Under proper \conditions the striations will e gialize the selves by. the flow of the enamel oltthe coating hereby the paper comes from the machines with a smooth coating of enamel over the entire surface to which the coating has been applied.

The equalizer roll indicated at 82 in Fig. 6 is provided with a convoluted surface by winding a wire 84 spirally about the roll. A smaller wire 86 is then superposed upon the wire 84. The wire 86 is positioned between the convolutions of the wire 84. The convoluted surface shown in Fig. 4 provides a deposit of enamel upon the paper having striations 88 as indicated in Fig. 5. The equalizer roll shown in Fig. 6 provides a coating of enamel having striations 89 as shown in Fig. '7. The distance material must move sideways to smooth the striations of Fig. '7 is less, compared with the weight of the coating, than in Fig. 5.

In Fig. 8 the web 81 passes over a coating roll 88 and under an equalizerfroll 92. The web 88 then passes under a brush 94. The brush has an oscillatory movement and functions to.fiatten the coating of enamel should it be too stiff to assume a smooth surface through the forces of gravity. surface tensions, or capillary action. With certain grades of paper the single brush of Fig. 8 may secure a perfect finish with enamels of a consistency that prevents complete smoothing without any assistance.

When the mechanical load of the paper on the equalizer is such that there is any question of rigidity involved, the equalizer may be supported on a beam 93, as indicated in Fig. 9.

In Fig. 10 the webs 96 and 88 pass under an idle roll I88 and are separated by means of a shoe I82. The web of paper 98 passes over a coating roll I84 and an equalizer roll I86. The webs 96 and 88- pass in contact around an idle roll I88 and over an idle roll I I 8. The webs are again separated by means of a second shoe II2, while the web 98 is moved over a coating roll H4 and an equalizer roll II6. After the webs 96 and 98 have passed beyond the shoe IIZand the equalizer II6, they are moved together to the drying device, each carrying a deposit of enamel upon one side. Enamel containing pans I and I I5 are associated with the coating rolls I84 and H4. The shoes I82 and H2 lift the webs not being coated while the webs being coated receive their deposits of enamel and pass over the equalizer roll.

I have secured good results according to the foregoing disclosure with equalizer rolls driven in the same direction as the paper but at a ma-' terially lower speed. a

In Fig. 11 I have indicated'a web of paper II8 as moving in the direction indicated by the arrow I28 and over an equalizer roll I22 which rotates slowly in the direction indicated by the arrow I26 opposite to the movement of the web. The equalizer roll is provided with a surface according to Fig. 6, made up of wires I29 and I38, as shown in Figs. 12 and 13. The enamel at I24 before equalizing piles up in the trough at I25 and is carried around to I28 to be redeposited. Referring to Figs. 12 and 13 it will be obvious that the serrations of the wires at the point of redeposit have shifted laterally from what they were at the first calibration. Thus the material brought up to I28 is a striated mass in which the striations are mismatched with those of the first calibration to produce a combined mass of much less depth of striation compared with the mass. The offset between the position of the striations of Figs. 12 and 13 may be increased by a multiple pitch winding as-in Fig.' 14 where a quadruple pitch is indicated and the amount of the second deposit may be increased or controlled by the use of a bath I23 for the equalizer I22.

In Fig. 15 the paper is not held against the equalizer by its own tension but by an opposing roll I32. This eliminates any uncertainty due to depending on paper tension forcontrolling the action.

In Fig. 16 the sheets 14 and 16 from the system of Fig. 1 are illustrated as subjected to simultaneous drying on both sides of both sheets. The upwardly directed jets I34 and I36 in the ducts I38 and I 48 carry the paper, while downwardly directed jets I42 and I44 in ducts I48 and I46 dry the upper surfaces at the same time. This saves space and the principle may obviously be extended to drying more than two vertically spaced sheets.

In Fig. 17 I have illustrated two equalizers I48 and I58 arranged'in series. Transverse adjustment of the second equalizer makes it possible to cause the equalizer I50 to fill in the grooves left by the equalizer I48.

The use of equalizers according to the invention makes possible much more delicate control of margins and the application of difierent colors to difierent portions of the same side of a web. In Fig. 18 I have illustrated an applying roll I52 delivering a coating to a web M3. Blocks I56 transversely slidable on a square rod I58 may be adjusted by screw and nut means IEO engaging the frame I62 to position the sheet metal shields cisely than could be done even by hand on a small scale.

Accurate control of the process requires precise adjustability of all the equalizers, which may obviously be provided in any one of the various simple mechanical ways.

Without further elaboration, the foregoing will I so fully explain the gist of my invention that others may, by applying current knowledge, readily adapt the same for use under various condi tions of service.

What is claimed is, 1. The method of producing coated paper whic comprises; moving a web of paper; applying to said web at a predetermined point wet coating material substantially in excess 01 the amount finally desired; continuing the movement of the wetted web out of contact with the applying instrumentality; drawing the wetted web under its own tension over a striated calibrating and equalizing bar, to remove excess coating and calibrate the thickness of the remaining coating at all points transversely of the web by the contact between the web and the striated bar only;

. permitting the striated and calibrated coating to remain wet long enough for the striations to disappear; and subsequently drying the coated web.

2. Apparatus for performing the method of JOSEPH H. WOOD. 

